The present invention relates generally to refrigeration compressors and more specifically to such refrigeration compressors of the reciprocating piston type which employ a suction gas muffler for attenuating noise resulting from the operation thereof.
In design of high efficiency compressors, it is important to provide relatively unrestricted suction gas flow to the compressor. However, this suction process results in the generation of substantial noise due both to the rapid flow of suction gas into the compressor as well as operation of the intake valving. Accordingly, it is desirable to provide some form of noise attenuating means in the suction gas flowpath. However, it is also important to overall compressor efficiency to assure a relatively free unrestricted flow of suction gas to the compressor. Accordingly, the use of various forms of restrictors and baffles in the main flowpath is undesirable in that such devices may create excessive flow losses requiring larger conduits be utilized to prevent compressor suction starvation.
As present practice requires the design of compressors to be as compact as possible, the available space within the assembly imposes several constraints on the size of suction mufflers. Further, because of these space limitations, it is often necessary to extend the suction gas conduit in close proximity to the discharge muffler and conduits. Accordingly, as the discharge gas is relatively hot due to the compression process, it is desirable to minimize heat transfer to the suction gas so as to maintain a high volumetric efficiency.
Accordingly, the present invention provides a refrigeration compressor having an improved suction gas muffler which effectively attenuates noise generated from the above-mentioned sources while still enabling relatively free unrestricted flow to the compressor. The suction gas muffler of the present invention is of the side branch type and comprises a relatively large diameter conduit having a housing secured thereto which defines a pair of side branch chambers each of which may be tuned to a different fundamental frequency. A pair of longitudinally spaced openings provide communication with each of the respective chambers and serves to define an impedance tube therebetween which may be tuned to attenuate a third fundamental frequency. Integrally formed baffles and ribs within each of the chambers further aid in noise attenuation by eliminating standing waves within the chambers as well as enhancing the rigidity of the muffler. The muffler is preferably fabricated from a polymeric composition so as to minimize heating of the suction gas being supplied to the compressor. Further, the use of such materials enables the suction conduit and muffler to be very inexpensively fabricated by suitable forming means such as for example injection molding.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.